Best model to simulate flow of items 2 ways simultaenously

Question

question

JIANYUAN, HALLEY L asked Feb 14, '20 JIANYUAN, HALLEY L commented Feb 20, '20

Best model to simulate flow of items 2 ways simultaenously

What is the best 3-D model to simulate the flow of items both ways simultaneously?

The model should be similar to people walking on the pavement whereby they can pass each other, with a limit of people on the pavement to be set (ie sum of people moving in both direction, assuming speed does not change with the number of people) where they would wait if the limit is reached.

I've tried processor but it could only replicate the flow of items in one direction but not both. The reason why I couldn't proceed with this having 2 process list to simulate both direction is because there is 6 different sources with movement in between them and they would pass other sources (places) which will add on to the limit of the processor as well and couldn't be ignored (road).

The travel node network would not work as there are many executers to set and they would arrive and move at random intervals. Currently the model should assume enough executers for items (everyone) arriving which would means too many executers to be placed in each nodes and they would move differently at each nodes.

Software Version:

FlexSim 20.0.0

flowitem

Answer 1 · 2020-02-14T20:32:41Z

tannerp answered Feb 14, '20 JIANYUAN, HALLEY L commented Feb 20, '20

Hi @JIANYUAN, HALLEY L,

I'm not sure exactly what kind of process you're modeling, but I've developed a couple examples of how you might go about limiting flow in a model.

The first uses processors and a label value. When items enter either processor, the label value is incremented by 1. Then, when an item leaves a processor, the label value is decremented by 1. There is a Process Flow listening to the Processors so that if the label value is 10 or higher, the inputs are closed to both processors, signifying that the area (road) is full. Then, when items exit either processor and the label value decreases below 10, the inputs are opened on both processors and more items are accepted. The total number of items in this processor zone must be 10 or less.

An alternative method would be to use a Traffic Controller as demonstrated by the operators moving boxes through 4 different flows while sharing one path. The Traffic Controller object limits the number of operators on the path to 2 at a time.

Hopefully one of these demos at least gives you an idea to start with.

traffic-control-examples.fsm

traffic-control-examples.fsm (62.0 KiB)

· 3

JIANYUAN, HALLEY L commented · Feb 15, 2020 at 04:10 PM

Hello @tanner.p

Thank you for answering my queries. Can we further discuss the process and label values? I've attached a picture to illustrate (The traffic controller method would require too many operators to set and doesn't seems feasible for my model).

From the model attached, processor 1 seems to be the "main" player as the average content processed is higher than that in processor 2, is there a way to make them closer to each other?

Also, may I know if the "names" of items released from each source affects the label values? If source at SS releases an item "TONIE"/"NIE", as it passes through the processor to a queue at NS before processed to NIE, will the names be changed? Sorry if this is too simple of a question but I face many problems when looking at which items to pull/sent to the correct processor.

Thanks for taking your time to answer!

0 ·

flexsim-model.png (55.1 KiB)

tannerp JIANYUAN, HALLEY L commented · Feb 19, 2020 at 10:43 PM

I took a closer look at the model to see why Processor 1 is favored and it's likely just because the input port for Processor 1 is opened before Processor 2 (only by a fraction of a second). Because of this, the items are more readily accepted at Processor 1. I'm not sure if there's a way to mitigate this other than maybe implementing a round robin token-sending logic somewhere.

To answer your second question, it's not important what the names of the tokens are in comparison to their labels. Names are just used for looking at detailed statistics about certain items if you need that.

Another thought I had after looking at your chart was using Process Flow resources to limit the number of items. For example, if an item is supposed to move from NS to SS, it will try to acquire SS, but if SS is acquired by something else, then it will have to wait before it sends the item.

Have you used Process Flow like this before?

0 ·

JIANYUAN, HALLEY L commented · Feb 20, 2020 at 04:51 PM

Thanks for taking your time to answer and clarifying the input part of the process, I thought that was the case...

The acquiring part seems to be of less importance as there would be many movement between each "nodes" for each run. NS and SS are representative of a location so there can be many tokens in each locations.

The idea of the model is to track the names of the tokens to understand the arrival rates/ throughput/ processing time at each location first before limiting the flow and obtain other data via adding waiting times, leaving queue etc.

This is the first time I've used FlexSim, I've only gone through the tutorials in the Manual. I was trying to model the flow by individual processes/nodes searching online and doing certain tests until I thought of posting a question to see if similar cases have already been done.

Thanks for helping me understand how to better simulate the model, I will start building the model.

Cheers! =D

0 ·

question